This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

An extensive, if one-sided, history of U.S. law enforcement's war on drugs.

This striking Victorian Home with its 113-foot turret is best known as the site where abolitionist John Brown was executed in 1859.

Home to items never before seen by the public.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The national park was once a plantation estate.

The narrowest house in America is seven feet of pure spite.

The walls of the iconic dome are hollow and have a secret stairway.

FDR's Art Deco hospital tower was hopelessly inefficient.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

A reproduction of earth's many biomes.

There aren't too many operational funiculars around, but Pittsburgh has two!

Nothing says indulgence like a 1,500-pound chocolate castle.

The world's largest collection of the world's largest objects is in one small Illinois town.

Quirky water tower advertises the long-gone Brooks Tomato Products Co.

The future of roadside attractions is this sci-fi soda mecca that is home to a 66-foot tall neon pop bottle.

This unusually circular centenarian barn became a Route 66 icon.

This Memphis recording studio launched the careers of Jerry Lee Lewis, Johnny Cash, and Elvis Presley.